Welcome to CCUK. I think your best bet would be to keep looking at "Corsa breaking" on ebay (Corsa C isn't specified so often so, although you're scrolling past a lot of useless Ds and Es, the alternative is that you miss a lot of Cs on there). If you see one with a manual sunroof, make an enquiry. If you select order by "newly listed", then your future searches don't take so long. I used to search all Corsa used bits for a few years (got pretty much everything I want now, so not so much these days) and that's not something I've seen often and that particular look is not ringing a bell at all. You could search more specifically for sun roof handle, but that might take longer than messaging breakers with a likely looking car.